Air-operated reciprocating piston pumps are in general well known and have been in widespread operation for many years. Such pumps have traditionally suffered from two problems which are closely interrelated to the point where the solution of one problem typically exacerbates the other. First, in the normal operation of such pumps, the expanding air in the air motor becomes quite cold and, as it exhausts, cools the valve and exhaust passages tending to build up ice in the valve and exhaust passages. If the pump should be operated at relatively high cycle rates and/or high pressures for an extended period of time, the ice build-up can be sufficient to slow or completely stall operation of the pump. Once the pump has stalled, it may need anywhere from one to several hours to thaw the blockage from the passages noted.
Such pumps have also typically produced relatively high noise levels in normal operation. Attempts to muffle the noise by restricting the exhaust of such motors using conventional muffling technology has typically led to substantially decreased performance, efficiency and increased ice build-up due to the increased restriction in the exhaust stream.
It is therefore an object of this invention to produce an air motor which is substantially quieter than existing state of the art machines.
It is yet a further object of this invention to produce an air-operated pump which is capable of operating for extended periods at high cycle rates, high pressures without icing or other decrease in performance.
It is yet a further object of this invention to provide such an air-operated pump which operates efficiently by virtue of low back pressure compared to conventionally muffled air motors.
It is yet a further object of this invention to provide an air-operated pump which may be easily and inexpensively manufactured.